Anomaly detection is crucial for CAD. Whole slide image (WSI) searching is preferred for CAD to avoid false negatives but is limited by its image acquisition and processing speed. Most of the existing approaches for WSI screening use low-magnification images in order to reduce image acquisition time. Thus, image quality becomes degraded. Information contained in low-magnification images is less than that in high-resolution ones, thus imposing limitations in accurately segmenting and classifying anomalies. Moreover, large searching area in WSI screening introduces more false positives, which affect diagnostic results as well.
Using multiple imaging modes in WSI screening is potentially useful to reduce false positives. At present, most products do not provide WSI analysis for evaluation and do not support multiple imaging modes. They only use samples from a single setting (e.g., same exposure time, same experiment) for classification. Besides, most of them are machine dependent, which are not easy to be adapted to new hardware settings.
Typically, two imaging modes are used in current products for image analysis: the fluorescence (FL) mode and the brightfield (BF) mode. However, both modes have their own shortcomings. For the FL mode, despite a relatively high sensitivity among different imaging modes, objects other than anomalies often emit green fluorescence as well under excitation. It may cause false positive results, thereby affecting accuracy of diagnostic results. For the BF mode, which results in a low contrast when compared to the FL mode, calibration is required due to color variation of dye in samples from different experiments.
Thus, there is a need in the art for a technique that supports multiple imaging modes and makes use of multi-mode results in enhancing accuracy in anomaly detection. The technique is especially useful in anomaly detection for WSIs.